Unit 7 - Bacterial MVPs Flashcards
proteobacteria (gram, characteristics, metabolism)
- often most commonly encountered bacteria
- related to mitochondria
- metabolically diverse
– chemolithotrophs
– chemoorganotrophs
– phototrophs
(many diff metabolisms, diff sources of e-) - morphologicaly diverse
what are the 5 phylogenetic groups of proteobacteria
alpha, beta, gamma, delta, epsilon
α β γ δ ε
proteobacteria named after Greek god ___
Proteus (as changeable and dynamic as the ocean)
proteobacteria lineage/categories (include metabolism type)
ancestral phototroph->
phototroph:
- alpha purple bacteria
- gamma purple bacteria
- beta purple bacteria
loss of photosynthetic ability:
- epsilon purple bacteria (all chemoorganotrophs)
- delta purple bacteria (all chemoorganotrophs)
proteobacteria - type of photosynthesis, inhibited by? wavelength determined by?
anoxygenic photosynthesis
- photosynthesis is inhibited by O2 (but some can grow aerobically)
- not like cyanobacteria!
- wavelengths determined by specific bacteriochlorophylls and carotenoids (many diff colours)
purple sulfur bacteria blooms
photoautotrophs of Gammaproteobacteria
- oxidize H2S to S^0 during photosynthetic CO2 reduction in anoxic lake water
- accumulates in inclusion bodies
- photolithoautotrophs
- stored in periplasm or outside cells, disappears when oxidized to sulfate
Winogradsky column description
- mud column, developed by Sergei Winogradsky
- photoautotrophs of Gammaproteobacteria
- high sulfur preferred by purple sulfur bacteria, low sulfur preferred by purple non-sulfur bacteria
- sulfur as a source of e-
- light as energy
- CO2 as carbon source
- H2S source due to anaerobic respiration (with SO4^2- as e- acceptor)
- sulfate reducers make sulfide, which floats up to help higher organisms survive
Winogradsky column order (bottom to top)
BOTTOM (H2S)
- sulfate reducers, fermenters, cellulolytic bacteria
- green sulfur bacteria
- purple sulfur bacteria
- purple non-sulfur bacteria
- cyanobacteria and algae
water
air
TOP (O2)
methanotrophs and methylotrophs (oxidation, env)
methylotrophs oxidize C1 compounds
- no C-C bonds (non-organic)
- e.g., CH4, HCOOH
methanotrophs are methylotrophs capable of oxidizing methane (CH4 to methanol)
- methane monooxygenase (MMO)
- intracytoplasmic membranes! (surface area)
- obligate C1 utilizers
- obligate aerobes, often microaerophilic
- widespread in soil and water, morphologically diverse
methanotroph env
- aquatic and terrestrial habitats
- often at interface between anoxic (where methane is formed) and oxic (needed for respiration) zones
– frequently observed at the thermocline (e.g., lake water columns)
- found in cattle rumen, swamps
– although high CH4, O2 often too low
methanotrophs vs methylotrophs
Methanotrophs are methylotrophs capable of oxidizing methane (CH4 to methanol)
nitrifiers (rxn, characteristics)
NH3 -> NO2 -> NO3
- use reduced N compounds as energy sources (e- donors)
- intracytoplasmic membranes also
- capable of autotrophic growth (chemolithoautotrophs)
- scattered in 4 of 5 subdivisions
nitrifiers subdivisions (species)
- scattered in 4 of 5 subdivisions
Nitrosococcus and Nitrosomonas (Nitroso-)
- ammonia oxidizers
- ammonia monooxygenase
Nitrobacter and Nitrospira (Nitro-)
- nitrile oxidizers
- nitrile oxidase
What is FISH? Details, probe colour meaning, rxn
- detecting nitrifying bacteria in activated sewage sludge by FISH
- two types of bacteria co-occur in nature
- fluorescent dye-tagged phylogenetic probes
– Red: ammonia-oxidizing bacteria
– Green: nitrite-oxidizing bacteria
NH3 -(red)-> NO2 -(green)-> NO3
what is the species exception to the nitrification process?
Comammox bacteria (Nitrospira)
NH3 -> NO2 -> NO3
- complete nitrification
Pseudomonads characteristics (taxonomy, morphology feature, env, etc)
heterogeneous group with evolving taxonomy
- Pseudomonas recently split into Pseudomonas, Burkholderia, Ralstonia, Commamonas, etc
aerobic chemoorganoheterotrophs
- polar flagella (distinguishes from enterics)
nutritionally and ecologically versatile
- soil, water, eukaryotic hosts
- may infect plants and/or animals
some are fluorescent!
- Pseudomonas aeruginosa or Pseudomonas fluorescens
- Pyoverdin produced as a siderophore (sequester iron from host)
___, ____, and ____ use internal membranes for energy generation
nitrifiers, purple bacteria, methanotrophs use internal membranes for energy generation
both purple sulfur and purple nonsulfur bacteria can use sulfur for ___
e-
N2 fixers characteristics
free-living, N2-fixing bacteria
- fix N2 into biomass; most are aerobes
- nitrogenase (reduces N2 to Nh3) is irreversible inactivated by O2
- thick capsule slime layer, very high respiration rate maintain low internal conc of O2
agrobacterium and rhizobia (not free-living)
- members of Alphaproteobacteria:
– Family: Rhizobiaceae
– Gram-neg, aerobic rods
– generally plant-associated
- incl Agrobacterium (parasitism)
– Crown-gall disease (tumours)
– don’t fix N
– Transfer DNA (T-DNA) invades eukaryotic genome (inter-kingdom), allowed by “vir region”; also digests opines made by plants through opine catabolism genes - Rhizobium, Sinorhizobium, Azorhizobium, Mesorhizobium, Bradyrhizobium (mutualism)
– symbiotic nitrogen-fixers
– root nodules
– associated with legumes!!!
rhizobium (root nodule formation)
- plants express flavonoids
- bacterial nod genes expressed
- infection thread formed to invade root
- nodule forms, providing a low O2 env
- root cells form leghemoglobin to assist
plant provides C compounds and photosynthase to bacteria, while bacteria provide ammonium
step summary: flavonoids, nod factor, root curl, infection
enterics
enteric bacteria
- all found in Gammaproteobacteria (e.g., Salmonella, E coli)
- facultative, oxidase negative, peritrichous flagella
- coliforms are gram-neg, non-spore forming, lactose-fermenting, producing acid and gas at 37 deg C
– some associated with feces (fecal coliforms) and can be warning signs of pathogens
– many enterics are pathogens
Deltaproteobacteria (2, characteristics)
Bdellovibrio bacteriovorus
- chemoorganoheterotroph
- “bdello” = leech “bacteriovorus” = bacteria eater
- small, HIGHLY motile (vibroid shape)
– 100 cell lengths per second
- preys on other bacteria (Gram-neg)
– virus-like life cycle
Gliding Myxobacteria
- complex behaviour and development
- large chromosome
- INTERcellular communication
- vegetative cells have gliding motility (lyse other cells for nutrients, chemoorganoheterotrophs)
- slime trails
- nutrient limitation leads to differentiation, cooperation (requires quorum)
– multicellular, pigmented fruiting bodies (antioxidant)
- fruiting bodies filled with myxospores
env: decaying wood, dung pellets (visible w magnifying glass)
Bdellovibrio life cycle
- Hydrolytic enzymes produced in periplasm
- 3-6 progeny per lysis, more from larger cells, filaments
- Attachment, penetrate periplasm, degrades cytoplasm/cell membrane, consuming cell material, elongation inside, divide to make more, prey lysis
Myxobacteria life cycle
fruiting body needs (1) starvation (2) quorum (enough organism mass to form fruiting body)
vegetative cycle can aggregate into mound -> fruiting body -> make myxospores -> germinate
chemical induction can also make vegetative cells into myxospores
firmicutes and actinobacteria are also known as?
firmicutes = low GC
actinobacteria = high GC
spores in this topic refer to? meaning?
refer to endospores, so ones with must all be Gram-pos
Gram-pos bacteria (non-sporulating)
Staphylococcus and Micrococcus
- aerobic growth, catalase positive
- resistant to drying + high salt
- 7.5% NaCl can select for them
- often pigmented
Staphylococcus
- firmicutes division (low GC)
- found on animals (SKIN)
Micrococcus
- actinobacteria division (high GC)
- isolated objects, dust, SKIN
Lactic acid bacteria
- rods and cocci
- aerotolerant anaerobes
– no ETC (no respiration)
– substrate level phosphorylation only (fermentation)
- complex nutritional requirements (fastidious, limited biosynthetic capacity)
which species of lactic acid bacteria are in processes of human interest? for what?
- Streptococcus pyogenes (necrotizing fasciitis)
- Streptococcus pneumoniae (bacterial pneumonia)
- Fermented food products (buttermilk, cheese: e.g., Lactococcus)
- Dental caries
homofermenters vs heterofermenters
lactic acid bacteria
homofermenters only make lactic acid
heterofermenters make lactic acid, ethanol, and CO2
Gram-positive bacteria (sporulating)
Bacillus group (facultative or obligate aerobes)
- can degrade polymers (amylases, nucleases, lipases)
- produce antibiotics (related to sporulation process)
- some make crystal toxins
– kill insect larvae
– Bacillus thuringiensis (BT toxin)
- some can infect humans, other animals
– Bacillus anthracis (anthrax)
Clostridium group (strict anaerobes; no e- transport)
- diverse fermentation substrates and products
- important for industry (Acetone, etc)
- some fix N2 (no need to protect nitrogenase from O2 since anaerobic)
- some make toxins that cause human disease
agricultural importance of Gram-pos bacteria (sporulating)
Bacillus thuringiensis
parasporal body
- crystalline protoxin (Cry protein)
- converted to toxin in larval insect gut (why it’s called pro-toxin
- BT toxin
- endospore next to the crystal
botox species
Clostridium botulinum
3 positions of endspores
terminal
subterminal
central
actinobacteria (high GC Gram-pos)
tuberculosis (Robert Koch) - Mycobacterium, tuberculosis
- contain mycolic acids in cell wall (waxy)
– long fatty acids
– acid-fastness (need heat for dye to penetrate; hard for drugs to penetrate)
many are human pathogens
- Mycobacterium leprae (leprosy)
– hosts: humans and armadillo (temp)
– can’t be cultured
- Mycobacterium tuberculosis
– hard to culture
resistant to many cheicals
Mycobacterium species and most other actinobacteria are ?
normally occurring soil bacteria
many are harmless, many can cause disease
filamentous actinobacteria
incl Streptomyces and relatives
- filamentous, branching mycelia
- desiccation-resistant spores
– CONIDIA (formed in sporophores)
- GEOSMINS = make soil/earthy smell
- make antibiotics (stimulates growth at low conc)
sporophores aka? what do they grow into? steps?
AKA aerial hypha
grow into spores (conidia)
growth phase, tip curls, partitioning of tip, cell walls thicken and constrict, spores mature
what is used for taxonomy for Streptomyces groups?
type of sporebearing structures
Cyanobacteria (charcateristics)
gram-neg
- distant phylogenetic relationship to gram-pos bacteria
- cell envelope structure similar to gram-neg
- oxygenic phototrophs
- gliding motility
- morphologically diverse
- have chlorophyll a (like algae and plants)
- also have phycobilins (bag-like membranes)
– accessory pigment
– phycocyanins (blue)
– phycoerythrin (red) - photosynthetic pigments within thylakoid membrans
what do some cyanobacteria make? (unique & cool) rxn
what do they do?
some filamentous cyanobacteria make heterocysts!
- differentiated cells capable of N2 fixation, have thick wall to exclude O2 (nitrogen fixation)
- not used for anything else
N2 -> NH3 –> Glutamine
vegetative cells around it obtain organic carbon from CO2 by light energy capture, then sends fixed carbon to heterocysts
